# Environment Variables (CybusMQ)

Configure CybusMQ to match your deployment requirements using environment variables.

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CybusMQ uses the original VerneMQ variable names.
{% endhint %}

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### Prefer Helm Values Over Environment Variables in Kubernetes Deployments

For Kubernetes deployments, configuration is primarily done through Helm chart values. Environment variables should only be used if there is no corresponding Helm value.
{% endhint %}

The following environment variables are available for simple configurations. If you need further options, you must provide your own configuration file in which you can use all VerneMQ configuration options.

## Environment Variables

| Environment Variable                               | Description                                                            |
| -------------------------------------------------- | ---------------------------------------------------------------------- |
| `DOCKER_VERNEMQ_ALLOW_REGISTER_DURING_NETSPLIT`    | Allows clients to connect even if the cluster is incomplete.           |
| `DOCKER_VERNEMQ_ALLOW_PUBLISH_DURING_NETSPLIT`     | Allows clients to publish even if the cluster is incomplete.           |
| `DOCKER_VERNEMQ_ALLOW_SUBSCRIBE_DURING_NETSPLIT`   | Allows clients to subscribe even if the cluster is incomplete.         |
| `DOCKER_VERNEMQ_ALLOW_UNSUBSCRIBE_DURING_NETSPLIT` | Allows clients to unsubscribe even if the cluster is incomplete.       |
| `MAX_OFFLINE_MESSAGES`                             | Maximum number of messages stored while a client is offline.           |
| `MAX_ONLINE_MESSAGES`                              | Maximum number of messages stored while a client is online.            |
| `PERSISTENT_CLIENT_EXPIRATION`                     | Defines how long persistent sessions are kept without client activity. |
| `DOCKER_VERNEMQ_LOG__CONSOLE__LEVEL`               | Configures the console log level.                                      |


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